Quantum computing is set to revolutionise the way we work. Trouble is, it could crack any of today's security codes in a fraction of a second, says Charles Arthur.When bankers and spies begin to worry about advances in computing, the rest of us would do well to take notice. What makes them edgy are the advances being made in "quantum computing", which is, as might be expected from the name, as entangled and confusing a field to understand as the branch of physics on which it is based - quantum mechanics.

But a banker doesn't need to be able to understand quantum physics to know that a computer capable of breaking any of the world's encryption codes as soon as it is turned on could mean serious problems for the bank's financial system. Systems used to transfer funds around the world every day rely on encryption that takes milliseconds to encode, but, in theory, millions of years to crack, by even the most powerful computers. And governments routinely use encryption to pass on secret messages.